1. Field of the Invention
This invention relates to a power cord. In particular, it relates to a power cord for an appliance that has a built-in leakage current detection conductor for detecting a leakage current in the power cord.
2. Description of the Related Art
With the wide use of household electrical appliances, such as air conditioners, washing machines, refrigerators, etc., more attention is being paid to the safety of using such appliances. An appliance typically has a power cord of one meters or longer. As shown in FIG. 1, such a power cord is made of three copper wires 11, 6 and 8 for carrying power, three insulating layers (made of rubber or plastic) 10, 5, and 7 surrounding the respective copper wires, two metal sheaths 19 and 14 (made of thin copper wires woven together) surrounding two insulating layer, respectively, and an outer insulating layer 1 (made of rubber or plastic) enclosing the wires.
Such a power cord may age due to long-term use, or become damaged when the appliance is moved, which may cause a leakage between the phase line and the neutral or ground lines in the cord. Such leakage current may cause sparks, which may cause fire and property damages. To quickly and accurately detect leakage current in the power cord, an additional conductor is provided and electrically connected to the metal sheath 19, 14. Leakage current can be detected by detecting a voltage on the metal sheath.
The metal sheaths are conventionally made by weaving thin copper sires. The cost of the power cord has increased due to the increase cost of the copper material.